The MARC Animal Core will serve the Center by purchasing, testing, breeding, maintaining and distributing animals to MARC investigators. The Animal Core will serve five major purposes: (1) Purchase and set up breeders to produce animals for the MARC Scientific Components;(2) Behaviorally test mice associated with the creation of short-term selection lines to be used by Scientific Components 5 and 6 (3) Determine animal distribution priorities and develop distribution procedures;(4) Develop new behavioral testing procedures and obtain animals on an as needed basis for new pilot projects or changes in direction as they occur;(5) Maintain a database that will track individual animals and post trait data for all MARC investigators to view and utilize. F1 or F2 mice that are the descendents of C57BL/6J (B6) and DBA/2J (D2) inbred strain mice will be used in Scientific Components 5 and 6, and Pilot Project 8B. The Core will breed F1 and F2 mice for use in these components. A set of replicated mouse lines selected for high and low methamphetamine (MA) drinking, and an independent set for high and low MA-induced sensitization will be created within the Animal Core for distribution to Scientific Components 5 and 6. B6 breeders will also be set up to produce the neonates to be treated in the Core for Pilot Project 8C. The Animal Core will be managed by Dr. John Crabbe, who is experienced in developing animal models of addiction, and will be capable of providing other strains or genotypes of mice for new pilots on an as needed basis. All animals will be housed in AALAC accredited animal facilities under the full-time supervision of a licensed veterinarian. Procedures are in place for the avoidance of viral and bacterial contamination, and a sentinel screening program is used to quickly identify contamination and avoid spread. Careful genetic record-keeping and identification practices for the maintenance of a large number of genotypes have been in place for several years. Key advantages of the Animal Core are cost savings associated with centralized development, behavioral testing and distribution of the selected line mice;controlled environmental conditions;genetic quality control; removal of animal production burden from Component Pis. Decisions about animal distribution will be centralized and based on a number of criteria, including date of request, whether the request is for a MARC project, scientific progress, and date of last distribution to that project. The Core will be able to distribute littermates across projects to minimize litter effects within studies, and increase the potential for crossexperiment association analyses. Core practices will strengthen the data generated by the MARC.